Mobile communication devices have become increasingly common in current society. The prevalence of these mobile communication devices is driven in part by the many functions that are now enabled on such devices. Increased processing capabilities in such devices means that mobile communication devices have evolved from being pure communication tools into sophisticated mobile multimedia centers that enable enhanced user experiences.
The redefined user experience requires higher data rates offered by wireless communication technologies, such as Wi-Fi, long-term evolution (LTE), and fifth-generation new-radio (5G-NR). To achieve the higher data rates in mobile communication devices, sophisticated power amplifiers may be employed to increase output power of radio frequency (RF) signals (e.g., maintaining sufficient energy per bit) communicated by mobile communication devices. However, the increased output power of RF signals can lead to increased power consumption and thermal dissipation in mobile communication devices, thus compromising overall performance and user experiences.
Envelope tracking (ET) is a power management technology designed to improve efficiency levels of power amplifiers to help reduce power consumption and thermal dissipation in a mobile communication device. In an ET system, an ET circuit may be configured to provide a time-variant ET voltage to a power amplifier(s) for amplifying an RF signal(s). To achieve a desirable efficiency and linearity at the power amplifier(s), it may be necessary for the time-variant ET voltage to track closely with a time-variant power envelope of the RF signal(s). In this regard, the time-variant ET voltage should increase and decrease according to the rise and fall of the time-variant power envelope.
The RF signal(s), along with the time-variant power envelope, may be generated in a transceiver circuit(s) and provided to the ET circuit and/or the power amplifier(s). Typically, the transceiver circuit(s) is coupled to the ET circuit and/or the power amplifier(s) via a two-wire serial interface known as an RF front-end (RFFE) bus. In a non-limiting example, the transceiver circuit(s) can be configured to function as an RFFE master on one end of the RFFE bus, while the ET circuit and/or the power amplifier(s) are configured to function as an RFFE slave(s) on the other end of the RFFE bus. In this regard, to help maintain close alignment between the time-variant ET voltage and the time-variant power envelope, it may be desired to minimize processing latencies associated with the RFFE bus.